1. Field
The present disclosure generally relates to optical telescopes and, in particular, to telescopes having multiple sensors sharing a common primary reflector.
2. Description of the Related Art
Optical telescopes are often built to accommodate a single instrument at a time with the mounted instrument observing the entire field of view (FOV) of the telescope. As it is common to make observations with a variety of instruments, such as imaging cameras, photometers, and spectrometers, these instruments must be swapped into the single mounting location. The process of swapping instrument may take up valuable observation time, if the instruments are changed during an observation period, and may require calibration of the newly installed instrument, further consuming time. In addition, there is always risk of damage when handling an instrument and so every instrument swap risks both instruments. Finally, it is impossible in such a system to make simultaneous observations within a FOV.
Some telescopes are designed to allow multiple instruments to simultaneously make observations of the entire FOV by providing a beam splitter in the optical path such that a portion of the light from the entire FOV is reflected by the splitter to a first instrument while the remaining light passes through the splitter to a second instrument. This type of system may provide different optical characteristics for the two instruments as the reflected light may experience different spectral filtering depending on the reflective and transmissive characteristics of the splitter.
Some telescopes are designed to allow multiple instruments to simultaneously make observations of portions of the FOV. For example, the Hubble Space Telescope (HST) carried five instruments that each observed a separate portion of the FOV of the telescope. The five instrument interfaces were not identical, however, and the optical paths from the primary mirror to the five mounting interfaces were not identical. The Wide Field/Planetary Camera, for example, could not be interchanged with the Faint Object Camera. The optical design of the HST did not produce real exit pupils in the optical path, thereby limiting the ability to block off-axis light reflected from internal structures.